Spark-plug



E. H. SCHWAB.

SPARK PLUG.

APPLICATION FILED MAR. 3. 1919.

UNITED l STATES PATENT OFFICE.

EDWARD H. SCHWAB, 0F SOUTH BETHLEHEM, PENNSYLVANIA.

SPARK-PLUG. l

To alla@ hom it 'may concern:

Be it known that I, EDWARD H. SCHWAB, a citizen of the United States,residing at South Bethlehem, in the county of Northampton and State ofPennsylvania, have made certain new and useful Improvements inSpark-Plugs; and I do hereby declare the followingto be a full, clear,and exact description ofthe invention, such as will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings; and to the figures ofreference marked thereon, which form a part of this speciiication.

This invention relates to spark-plugs for internal combustion engines,and has for its object to provide a composite insulation for spark-plugsin which porcelain and mica are employed.

A further object ofthe invention is to provide a spark-plug having aninsulation of porcelain and mica, in which a novel construction isemployed for mounting the porcelain and mica members of the insulationon the electrode spindle.

With these and other objects in vieW the invention consists of the novelconstruction of the electrode spindle; in the novel construction ofmounting the porcelain and mica members of the insulation, and incertain details of construction and combinations of parts, all of whichwill be first fully described and afterward specifically pointed out inthe appended claims.

Referring to the accompanying drawing:

The figure is a vertical sectional view of a spark-plug-constructed inaccordance with this invention.

Referring to the drawing by reference numerals:

1 indicates the spark-plug having a metal shell 2, threaded at 3 forconnection with a motor, and formed preferably hexagonal at 4 to receivea suitable Wrench. The shell 2 is internally chambered to receive theinsulation and is provided with an internal seat or shoulder 5 and has afemale threaded portion 6 to receive the male threaded portion 7 of thegland or bushing 9, said gland or bushing 8 being shouldered at 10 forengagement with the porcelain member of the insulation, as will bepresently described. i

Referring now to the insulation 11, it will be seen that the sameincludes an inner Specification of Letters Iatent.

Application led lMarch 3,

Patented Nov. 16, 1920.

1919. serial No. 280,339.

porcelain member 12, and an outer mica member 13. "lhe porcelain member12 is provided exterlorly with a shoulder 14 complemental to theshoulder 5 in the shell, and

is internally bored to receive the electrodespindle 15. As shown thisbore is preferably of three diameters the lowermost and smallestdiameter' 16 receiving the electroderod 17, while the central andintermediate diameter 18 isprovided with a female thread 19 to receivethe male threaded portion 20 of the electrode spindle 15, a shoulder 21being formed at the juncture of the said central or intermediatediameter 18 of the bore and the uppermost and largest diameter 22.

The electrode spindle 15 receives the electrode rod 17, and directlyabove the threaded portion thereof, is a flange or shoulder 23complemental to the shoulder 21 in the porcelain insulating member. `Asimilar flange or shoulder 24 is formed on the spindle 15 near the headthereof, between which shoulders 23 and 24, a wrapping of mica 25 ispositioned, as shown in the drawing. The outer end of the spindle 15 isthreaded at 26 to receive a suitable terminal head 27, while a flange 28is formed on the spindle directly under the said threaded portion 26thereof.

The insulation is assembled as follows:

A suitable gasket 29 is passed on the spindle 15 and against the flange28 thereof; the mica wrapping 25 is applied between the flanges 23 and24, and the mica washers which form the mica section 13 are then passedon the spindle and over and around the mica wrapping 25. The spindle 15is then threaded into the porcelain member 12, a suitable cement beingemployed at the threaded 1,5 is 'progressed'A into the porcelain member12 until the flange or shoulder 23 thereof is seated firmly on thecomplemental shoulder 21 in the porcelain. This threading of the spindle15 into the porcelain member 12 carries the mica section 13 down uponthe flat face 30 of the porcelain member 12, and tightly compresses themica washers 4thereofY between said porcelain member 12 portion thereof,and said spindle- In assembling the insulation in the shell, a suitablesoft gasket 31 is disposed on the seat or shoulder 5 to provide aas-tight joint between the insulation and t e shell. After theinsulation is inserted, a suitable gasket 32 is placed on the top of theporceain member l2, and the gland or bushing 9 is threaded into theshell with pressure sufficient to effectively seat the porcelain memberl2 on its gasket 31.

A ground electrode of any approved type is provided, as for instance, atransverse rod 33, having both ends embedded in the shell, and spacedfrom the central electrode rod ll to provide a suitable spark-gap.

The advantages iowing from the foregoing construction will be at orceapparent to those skilled in the art, as in a simple and inexpensivemanner, a particularly durable and eiiicient plug is provided; one inwhich the tendency of the porcelain to fracture is reduced to theminimum, and in which the mica components are remote from the injuriousaction of oil and the direct, intense heat of the flame in the motor. A

Having thus fully describedthe invention, I wish it to be understoodthat while the construction shown in the drawing and described in thisspecification discloses the preferred embodiment of this inventionnevertheless the same is susceptible oi changes and modifications in theconstruction and arrangement of the parts, and that I consider myselfclearly entitled to all such changes and modifications as fall withinthe limit and scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. A spark-plug includin a metal shell and gland, an insulation incuding an inner porcelain member and an outer mica member, the porcelainmember bein internally threaded, an electrode spin e passed throu h saidmica member and having a threaded portion for threaded connectlon withthe porcelain member, the spindle including means for retaining the micasection thereon, and a wrapping of mica encompassing said spindle andpositioned within the porcelain and mica members.

2. A spark-plu including a metal shell. an insulation ino uding an innerporcelain member and an outer mica member, the

' porcelain member being internally threaded,

an electrode spindlev passed through the mica section and includingmeans at its terminal end for retaining the mica section thereon, saidspindle including a threaded portion for threaded connectlon with theporcelain member to compress the mica member upon the porcelain member,and a wrapping of mica around the electrode spindle and within both theporcelain and mica members.

3. A spark-plu including a metal shell, an insulation lncIuding an innerporcelain member and an outer mica member, the porcelain member beinginternally threaded, an electrode spindle passed through the micasection and includin means at its terminal end for retaining t e micasection thereon, said spindle includin a threaded portion for threadedconnection with the porcelain member to compress the mica member uponthe porcelain member.

4. A spark-plug including a metal shell, a gland for threaded connectiontherewith, an insulation including a porcelain member having a flat faceto be vengaged by said gland, and including a mica section, saidporcelain section being internall threaded, an electrode spindle uponwhich the mica section is mounted and including means at its terminalend for retaining the mica section thereon, and including a threadedportion for threaded connection with the porcelain member to compressthe mica section upon the said flat face of the porcelain section.

5. A:sparkplug including a metal shell, an insulation including aporcelain member anda mica member, the plug including means for exertingpressure on the lain member to retain same within the shell, saidorcelain member being internally threadred, an electrode spindleincluding a threaded portion upon which spindle the mica section ismounted, the said threaded portion of the spindle being threaded intothe porcelain member and compressing the mica member upon the porcelainmember.

In testimony whereof, I aix my signature.

EDWARD H. SCHWAB.

porce-

